Fatty acids ar a class of poorly soluble, hydrophobic metabolites that are used as building blocks for complex membrane lipids, energy storage and energy production. Under normal circumstances, the total concentration of fatty acids in the cell are kept within strict limits. During certain pathological conditions (ischemia/reperfusion, diabetes) total fatty acid concentrations can increase dramatically (80%) in some experiments). It is thought that such concentrations of fatty acids will outstrip the capacity of the cell to remove them from the cytoplasm. The effects of these elevated fatty acids levels however is not well understood. Preliminary experiments in this laboratory have demonstrated that cytochromes c are affected by the presence of fatty acids at physiological levels. The UV-VIS spectrum of the protein changes dramatically upon binding. It was originally thought that this must involve specific rearrangement of the protein structure around the heme ring. Subsequent 1/H-NMR experiments have demonstrated that the methionine sulfur atom (bonded directly the iron) is shifted away from the heme ring upon the binding of fatty acids. Cyclic voltammetric experiments have shown that the redox potential of cytochrome c is shifted when fatty acids bind to the protein. These observations indicate that fatty acids may have an important role in controlling the electron transport function of cytochrome c. Structural implications also suggest that cytochromes may be an important component fatty acid metabolism as well. Specific research aims, based on this hypothesis, are to rigorously investigate the affects of fatty acids on the structure, function, and reactivity of cytochromes c. The interactions of cytochromes c from mammalian, plant, and microbial sources with fatty acids of varied structural features will be studied. Most studies will be with native cytochromes buy site-specific variants, supplied by other researchers, will also be investigated in order to provide a more detailed of the binding process through structural modifications of the proposed site. A variety of instrumental techniques will be used to this hypothesis. These include stopped-flow and temperature jump kinetic spectrophotometers, a rapid-scanning spectrophotometer, 1/H and 19/F NMR spectrometers (250MHz and 400MHz), HPLC, conventional diode array spectrophotometers, cyclic voltammetry, and oxygen sensitive electrodes.